Checking collimation at home (1 Viewer)

[WJC]

Hi Bill.

That's a shame for the current discussion but it's your knowledge and entirely up to you whether to share it or monetize it. I can understand both perspectives.

Interestingly this is the thread i've had most PM's from offering advice which is all most welcome, I might check in with the members concerned and post up some anonymised responses for the sake of the discussion.

Will

William,

I have been away since post 7. But I will try to answer William’s questions and a few other that came along the way. But first, I would like to support Binastro’s take on the matter. IF IT AIN’T BROKE ... DON’T FIX IT!

William: The aspect of monetary gain: I would certainly like to make a little money off my efforts. However, THAT’S NOT WHY I WROTE THEM! I wrote them so that I might stop answering the same questions night after night after night and then get up to a 40-mile commute in the nation’s 4th worst traffic. Besides, I have learned that so many people would rather rally around popular—but foolish and erroneous—information than by buying a cheap book from one who has a half century in the craft.

The first graphic shows you what you might see in a Mk5 collimator.

Your collimator might be a telescope ... backwards. The second photo is of Cory Suddarth doing collimation jobs at the Okie Tex Star party. He is using a C-8. You saw MY binocular mount in one of my previous photos. It’s Navy all the way. But photo 3 shows you what will work just fine.

You will need a low-power auxiliary telescope. The blue folder show the one Australian Bruce Davis made. So instead of two crosshairs, you might see two dots of light. If one is 20 times bigger that the other, it’s irrelevant. The center of a dot is the center of a dot; and that’s what you’re after.

Thorough instructions for using a Mk5 collimator is available in both books. They take up about a page and a quarter, as opposed another popular method that takes up 31 pages of text and graphics. I honor that contributor and mention him in one of my books. Still, I think the instructions frighten of those who could use the info.

Cheers,

Bill

 

[William Lewis]

Another response -

1. You MUST evaluate each of the two scopes separately for defects. A simple star test usually suffices. If one is problematic then it affects binocular vision...the normal use of a "binocular".

2. If both scopes are acceptable then I'd check the movement of the focusing arm. Inexpensive porros are prone to one side flexing more than the other, resulting in one side in focus and one side slightly out. This can be caused by poor design OR by the user pressing on the eye cups (with or without eyeglasses). I have a good porro and I once had a $100 6X32 porro. The good porro focus is perfect and not subject to user pressure but the cheaper porro was and I deliberately avoided pressing on the eye cups. Also...the way each scope travels during focusing is vital to a sharp image. I noticed that with the cheaper porro I could rack the focus fore/aft and alter the balance between the two scopes, sometimes considerably.

3. If it's OK at this point things get a bit more interesting. Collimation problems for me show up as eye strain and eventual fatigue. The eye/brain mechanism can compensate for collimation errors for only so long unless they are very minor. You can do a roof line test and the test you performed with points of light but my favorite is the simplest of all. I set the bin up on a tripod (or some other stable platform) and I view through it with both eyes at a fixed target I enjoy (flowers, etc.). I blink and move my eyes periodically but basically I want to know how long I can comfortably look through the binocular and see a nice sharp image. During the test I do not look away from the binocular! As the saying goes, "time will tell."

4. Last, but not least, consider your appreciation of good optics. Maybe, just maybe, the quality of this bin isn't measuring up against better bins you've used. Again, it's been my experience that once I used a really sharp bin those I once considered perfect are perfect no more.

 

[William Lewis]

Thanks to all for all your help with this, hopefully it will be a useful resource. I'm looking forward to giving all the methods my best shot!

Nature offered some assistance tonight as it often does to help in my case too. We don't get a huge amount of darkness before bed time round here but work stresses got me up in the middle of the night to a sky full of stars which were spectacular through my regular binoculars but even more spectacular through the srga's - twice as many stars...

 

[Bino Steve]

Respecting the experts here and those with many years of training and service to the optics world, I feel an analogy brewing within me... With the dawn of the automobile industry, we used to, and mostly had to, fix our own cars, then later it went to we can still fix a lot on our own cars but some things we couldn't anymore and other things we chose not to because maybe we had money and better things to do. Then later we come to today with almost no user serviceable parts in our cars. Each one of these eras is o.k. Each era had someone upset to see change. There is pride of a skill, of knowledge, and each passing generation cares less about those skills.I can relate as a former Piano Technician as the piano world went digital. I could chose to be bitter or move on. It's sad but it's going to be o.k. The HAM radio world has the same thing going on, and it's o.k. Most people don't fix stuff. They are affectionately called "appliance operators " And it's o.k. to be that. They are having fun. They can't fix their $3,000 computer based micro circuit board loaded HF rig anymore. They buy vintage stuff for dirt cheap if they want to tinker. But I tell you, go to a HAM meeting and just hear ad nauseum bickering about "the current state of the world" and " who's not doing something right" and it's no wonder its a dying hobby. What youngster wants that?
So, if you have an Alpha bino, enjoy it. If your eyes hurt, use the warranty, send it in, be happy. Non-Alpha bino, no warranty or no skills, no user serviceable parts...toss it or give it away..you knew the risks buying cheaper. If you want to tinker and learn about how to collimate or shim prisms etc..get some Thrift store treasures and have fun and don't flip out if no one gives a rip how you fix them. It's all good and everything will be o.k. No one should be offended that younger generations or even manufacturers don't care about past skills or knowledge. Its not personal. Ill say it again " its not personal " This is our world, we actually have the best optics ever to use, the best cars ever to use, the best HAM radios ever to use. I'd rather send my bad bino in and get a new one back instead of waste time on it. Im not touching an Alpha with my butter fingers. Enjoy the extra time you'll have. Less stress, make friends, move on from the past, accept changes in the industry as permanent. Find something exciting about current trends in optics and latch on to that. Share that excitement with some youngster. Expand the hobby to them and just accept that equipment repair knowledge is/ has faded away. It's going to be o.k. and yes I own a digital piano now, it's great and I can't fix a dang thing on it...but I'm fine. Cheers and respect.

 

[Hauksen]

Hi Bill,

I have addressed this many times in lectures, articles, and books since 1942.

Fascinating! What are the tolerances one needs to collimate a pair of binoculars to? Is there a way to measure the alignment of the hinge axle, or is it only observed indirectly by checking optical aligment at different IPDs?

I've sort of dabbled in similar calibration activities when trying to come up with a good way to mount a reflex sight to a spotting scope, I now realize.

Regards,

Henning

 

[WJC]

Thanks Bill. Swimming lessons it is!

What would your method be of overlaying 2 dots of light with the usual stuff people tend to have around there homes, what distance would you use between them and how would you set up the binoculars and at what distance with regard to the lights?

P.s the first book with the yellow cover (naming no names!) looks an interesting read for me, where's it available?

I'm kind of wondering where the huge post I had created—complete with 7 pages of text and several photos went.

 

[WJC]

Thanks Bill. Swimming lessons it is!

What would your method be of overlaying 2 dots of light with the usual stuff people tend to have around there homes, what distance would you use between them and how would you set up the binoculars and at what distance with regard to the lights?

P.s the first book with the yellow cover (naming no names!) looks an interesting read for me, where's it available?

The two dots through the binoculars and over the top of the binoculars. Bring those dot together in the upper and lower swing and you have it.

 

[WJC]

Hi Bill,



Fascinating! What are the tolerances one needs to collimate a pair of binoculars to? Is there a way to measure the alignment of the hinge axle, or is it only observed indirectly by checking optical aligment at different IPDs?

I've sort of dabbled in similar calibration activities when trying to come up with a good way to mount a reflex sight to a spotting scope, I now realize.

Regards,

Henning

Hi Hauksen:

‘Buy ya books ... send ya to school and still ya want more. Okie Dokie. Here ya go.

The first attachment is Dr. Johnson’s tolerance, which is what I use. The second shows 10 other standards.

ALL WILL GET THE USER TO A COLLIMATION PRECISION MORE STRINGENT THAN VIRTUALLY ANY OBSERVER CAN RECOGNIZE! ... ANY ONE!

The US Navy taught their OPTICALMEN to get it to 2 minutes of step, 2 minutes of divergence, and 4 minutes of convergence. If you knew their rationale why, you would understand. Too many people needing an ego stroke, will latch onto one above the others. For me, it is tantamount to hunting squirrels with a howitzer. But it seems that is what bino forums are all about; going to 9 places on Pi.

Please note the comment from the Armstrong Aerospace Medical Research Laboratory:

“Zero optical tolerance and zero tolerances for image differences are not practical: They would be too difficult and expensive to obtain and could not be retained in use.”

Bill

 

[Hauksen]

Hi Bill,

The US Navy taught their OPTICALMEN to get it to 2 minutes of step, 2 minutes of divergence, and 4 minutes of convergence.

Are divergence and convergence in the same axis, but one is minus when the other is plus?

How is "step" defined?

Regards,

Henning

 

[WJC]

Hi Bill,



Are divergence and convergence in the same axis, but one is minus when the other is plus?

How is "step" defined?

Regards,

Henning

Your first line is correct. Divergence is pretty hard for the eye / brain to deal with. That is why the stiffer tolerance. Convergence or crossover much less critical. Try crossing your eyes ... see?

Step is the also known as Dipvergence. and it's really hard to tolerate.

Some time-wasting people claim to seek the non-existent "perfection" in collimation. It changes with temperature and humidity. Therefore ... it can't exist, except between the ears of those who don't know what they are talking about. But it does keep bino forums running ... doesn't it?

Cheers,

Bill

 

[Hauksen]

Hi Bill,

Your first line is correct. Divergence is pretty hard for the eye / brain to deal with. That is why the stiffer tolerance. Convergence or crossover much less critical. Try crossing your eyes ... see?

Step is the also known as Dipvergence. and it's really hard to tolerate.

So condivergence is one axis, dipvergence is the second axis - what's the third axis you mentioned initially then?

Regards,

Henning

 

[WJC]

Hi Bill,



So condivergence is one axis, dipvergence is the second axis - what's the third axis you mentioned initially then?

Regards,

Henning

Convergence AND Divergence are on the X axis; step (or Dipvergence) is on the Y axis. If you "need" to test it ... you don't need to ... test it!

 

[Hauksen]

Hi Bill,

Convergence AND Divergence are on the X axis; step (or Dipvergence) is on the Y axis.

I think you mentioned "3-axis collimation" earlier ... what's the third axis then?

Regards,

Henning

 

[WJC]

Hi Bill,



I think you mentioned "3-axis collimation" earlier ... what's the third axis then?

Regards,

Henning

1: Objective 1. 2: The second objective. 3: The axle, which is the KEY to accurate collimation. EVERYTHING else—all the immature garbage on the Internet—deals with Conditional Alignment—not collimation. But I have been trying to teach this for 46 years. The engineers and the more erudite get it. Those who already KNOW IT ALL ...never will! They just know that bino forums run on OPINIONS and that the opinion of the seasoned craftsman is no different than that of the inexperienced wannabe optical god (small g)!

 

[Hauksen]

Hi Bill,

3: The axle, which is the KEY to accurate collimation.

How do you diagnose axle axis misalignment, then? That would seem to be the decisive step, I believe.

Regards,

Henning

 

[WJC]

Hi Bill,



How do you diagnose axle axis misalignment, then? That would seem to be the decisive step, I believe.

Regards,

Henning

Checking collimation will tell you that. Don't over-think things.

 

[jring]

Hi,

the methodology used by Will is correct, except for the artificial star might be a bit too close... I would recommend a quick look at the starry skies and repeating the test or a bit more distance.

Btw, this is not what is usually meant when people talk about star-testing a telescope (with binoculars the magnificatio is usually too low for a star test - that means observing a real or artificial star at high magnification and defoussing very slightly while observing the diffraction patterns shown. Those can tell an experienced observer about the kinds of aberrations present and a rough guess of their strength.

Joachim

 

[Hauksen]

Hi Bill,

Checking collimation will tell you that. Don't over-think things.

Can I check collimation in one go? I thought I only have a pair of "inverted telecope" at my disposal that can only check optical alignment of the binocular tubes.

What I am thinking is that I probably need to check optical alignment, change IPD, then re-check alignment, and from the potential optical misalignment measurements then derive the magnitude and orientation of the mechanical misaligment of the axle axis.

Regards,

Henning

 

[William Lewis]

Hi,

the methodology used by Will is correct, except for the artificial star might be a bit too close... I would recommend a quick look at the starry skies and repeating the test or a bit more distance.

Btw, this is not what is usually meant when people talk about star-testing a telescope (with binoculars the magnificatio is usually too low for a star test - that means observing a real or artificial star at high magnification and defoussing very slightly while observing the diffraction patterns shown. Those can tell an experienced observer about the kinds of aberrations present and a rough guess of their strength.

Joachim

I know it's science and not nonsense but star testing always looks like reading tea leaves to me - I have no idea of it's nuances.


What was interesting way that the distance (in terms of angular degrees) separating the centre of the blurry diopter light circle from the sharp point of light from the non diopter side looked to be the same distance as the separation between the 2 stars (that we're actually one star!) when looking up last night.

Still amazed how hard it was to see they were off during daylight.

 

[Ted Y.]

A very interesting thread.

If I am in some town store, can I do a preliminary check (how?) or better wait to be home and do the testing there?